I've not seen nor heard of that before, but run the SOLIDWORKS Rx > Diagnostics to check the graphics card & driver compatibility.
It looks like your text is using a different color. Since you're editing a part in-context, try changing that color value using Tools-Options-SystemOptions-Colors and modify the "Assembly, Edit Part" color setting which is roughly half way down the long list of scollable color choices..
Absolutely correct. Who would have thought to look there. I have no idea how my user changed this.